Bit



'1: 27, 1949. H. M. MORROW 5 BIT F iled March 8, 1946 2 Sheets-Sheet 1BY #w m.

Sept. 27, 1949.

H. M. MORROW 2,483,220

BIT

Filed March 8, 1946 2 Sheets-Sheet 2 INVEN TOR.

Patented Sept. 27, 1949 arr OFFICE Harry M. Morrow, Canton, Ohio,aasignor to The Bowdil Company Application March 8, 1946, Serial No.652,972 3 Claims. (Cl. 262-33) My invention relates in general tocutting bits and more particularly to bits for cutting coal or othersubstances.

In the mining of coal or other substances, a cleft is cut in the lowerlevel of the vein by means of a cutter bar around which revolves a powerdriven endless chain carrying a plurality of cutting bits arranged instaggered relationship relative to one another. These cutting bitsconstitute the subject matter of this invention. The shelf formed by thecleft is subsequently broken off by means of explosives or othersuitable methods. When cutting the cleft, in the interest of economy andthe saving of power, it is highly desirable that the cutting bits be notonly strong and durable, but also eflicient in operation and free fromdrag. Further, it is desirable that these bits present a cutting tipwhich is long lived and resistant to rapid wear in order that the powerdriven endless chain carrying the bits may be operated continually untila specific cut is completed. That is, it is desirable that the bits bedurable to withstand prolonged abrasive action in order to preventcostly delay in removing the endless chain machine from the cleft beforethe cleft is finished in order to replace worn bits.

Therefore, an object of my invention is to provide a cutting bit havingan extremely hard cutting tip.

Another object of my invention is to provide a cutting bit having atough and durable body and having an extremely hard cutting tip imbeddedtherein.

Another object of my invention is the provision of a hard metal insertfor the body of a cutting bit which will provide an extremely durableend cutting edge for the bit, and is protected against dislodgingimpacts by the tough body metal of the cutting bit.

Another obj ect of my invention is the provision of an extremely hardinsert for a cutting bit to provide a durable end cutting surface forthe bit with the insert automatically exposable by the I wearing away ofthe bit body.

Another object of my invention is to provide a cutting bit having steelside cutting surfaces inclined in the direction of travel for slicingcutting action, and having a hard metal cutting tip insert substantiallyperpendicular to the surface being cut to provide impact cutting.

Yet another object of my invention, is to provide a cutting bit with ahard metal insert at the cutting tip thereof, with the hard metal insertpositioned to contact a surface and cut the surface when the bit ismoving in a cutting direction, and

2 said bit having a protecting surface to protect the hard metal insertfrom dislodging from impacts when the cutting bit is moving in adirection other than the active cutting direction.

Other objects and a fuller understanding of my invention may be had byreferring to the following description and claims, taken in conjunctionwith the accompanying drawings, in which:

Figure 1 is a side elevational view of a rhomboidal shaped coal cuttingbit blank to be developed into a bit employing the principles of myinvention;

Figure 2 is a side elevational view of the rhomboidal shaped coalcutting bit of Figure 1 with a phantom outline at one cutting tip of agroove provided therein, and showing a portion broken alwtay at theopposite cutting end to reveal the s o Figure 3 is a fragmentary portionof a bit with a portion thereof broken away and showing greatlyexaggerated a layer of bonding flux on the surface of the slot walls;

Figure 4 is a view similar to the Figure 3 with a hard metal insert anda piece of bonding material positioned in the slot with the bonding fluxbetween the slot surface walls and the insert;

Figure 5 is a cross-sectional view along the line 5-5 of Figure 3;

Figure 6 is a cross-sectional view along the line 66 of Figure 4;

Figure 7 is a side and front view of the commercial finished product;

Figure 8 is a front view of the bit after a period of service, or afterbeing dressed by abrasive action;

Figure 9 is a side elevational view of a rhomboidal shaped coal cuttingbit blank to be developed into a bit employing the principles of myinvention;

Figure 10 is a side elevational view of the rhomboidal shaped coalcutting bit of Figure 9 with a phantom outline at one cutting tip of arecess provided therein, and showing a portion broken away at theopposite cutting end to reveal the recess;

Figure 11 is a fragmentary portion of a bit with a. portion thereofbroken away and showing greatly exaggerated a layer of bonding flux onthe surface of the recess walls;

Figure 12 is a view similar to the Figure 11 with a hard metal insertand a piece of bonding material positioned in the recess with thebonding flux between the recess surface walls and the insert;

Figure 13 is a cross-sectional view along the line l3-l3 of Figure 11;

Figure 14 is a cross-sectional view along the line M-l 4 of Figure 12;

Figure 15 is a side and frontview of the commercial finished product;

Figure 16 is a front view of the bit after a period of service, or afterbeing dressed by abrasive action;

Figur 17 is a side elevational view of a rhomboidal shaped coal cuttingbit blank to be developed into a bit employing the principles of myinvention;

Figure 18 is a side elevational view of the rhomboidal shaped coalcutting bit of Figure 17 with a phantom outline at one cutting tip of arecess provided therein, and showing a portion broken away at theopposite cutting end to reveal the recess;

Figure 19 is a fragmentary portion of a bit with a portion thereofbroken away and showing greatly exaggerated a layer of bonding flux onthe surface of the recess walls;

Figure 20 is a view similar to the Figure 19 with a hard metal insertand a piece of bonding material positioned in the recess with thebonding flux between the slot surface walls and the insert;

Figure 21 is a cross-sectional view along the line ll-2| of Figure 19;

Figure 22 is a cross-sectional view along the line 2222 of Figure 20;

Figure 23 is a side and front view of the commercial finished product;

Figure 24 is a front view of the bit after a period of service, or afterbeing dressed by abrasive action;

Figure 25 is a diagrammatic illustration of the relative position of acutting bit carried by an endless chain link, showing the bit in itsactive cutting position and in its backing drag position.

With reference to the drawings, I illustrate my invention in itspreferred embodiment as incorporated in a rhomboidal shaped coal cuttingbit. This invention, however, is not limited bits of rhomboidal shape,but may be readily employed in other types of coal cutting hits, as wellas in cutting tools for other purposes in which the mode of cutting issimilar. In the mining of coal, these bits are removably in the lugs ofan endless power driven chain which revolves around a cutter bar. Thisdevice is then moved against the face of a coal vein and a cleft is outunder the vein of coal. Each bit is adapted to contact the coal surfaceand 55 alloy steel comprising the bit l0 and the side carve a furrowtherein. .In carving its furrow, the tip of the bit is forced into thecoal and serves to chip out minute pieces of the coal to start thefurrow. The side edges of the bit serve to chip away the sides of thefurrow and widen the furrow in order that the next bit will be able todescend to the depth of the furrow and carve a new and deeper furrow.Thus; the tip of the bit receives considerably greater wear than thesides of the bit, and is subject to much more severe wearing conditionsthan the side. In the particular form of rhomboidal bit as illustrated,when one of the cutting points of the bit wears away, the bits arereversible in the holder, giving a double cutting life to the bit. It isextremely desirable to provide a cutting bit which is able to withstandthe extreme wearing conditions imposed and maintain an. active cuttingtip throughout the period of cutting the cleft in order that the cuttingoperation will not 4 to be halted in order to reverse or replace thebits.

In the Figures 1 through 8, I have illustrated one embodiment of myinvention. The Figure 1 is a side elevational view of a rhomboidalshaped bit in preferably constructed of tough alloy steel and similar tothe rhomboidal bit shown in Patent No. 1,677,950, issued to N. K. Bowmanon July 24, 1928, and Patent No. 2,217,347, issued to H. M. Morrow onOctober 8, 1940. both patents of which are assigned to the assignee ofthe present application. This bit If! is used as the bit blank inpreparing a bit employing the principles of the present invention.Figure 2 of the drawings illustrates in phantom and in a broken awayportion the depth and outline form of a groove which may be milled orotherwise cut into the tip of the bit. The cutting of the grooveproduces two side portions l4 and 15. After this groove II is cut, acoating of flux material I2 is coated over the surface of the groove II.This material l2 may comprise any of the well-known flux materials usedin bonding metals together. This flux material is illustrated in theFigures 3 and 5, greatly exaggerated for clarity. The next step inproducing my improved bit, is to place an insert 13 in the groove ll asillustrated in the Figures 4 and 6. The insert is held in placetemporarily within the groove I l by pinching the side portions 14 andI5 of the bit l0 together upon the insert l3.

The insert I3 is bonded in place permanently by a silver solder or othersuitable bonding material. In the illustration, I show a piece of silversolder l6 held in the groove in a position relatively near to the insertl3 by pinching in the side portions ll and IS in a manner similar tothat of the insert l3. The bit "I with the insert l3 and the bondingmaterial It held frictionally within the groove II is then placed in aheat treating furnace and elevated in temperature. During the time whichthe device is held at the elevated temperature, the bonding material I6is caused to become fluid and will work its way between the insert l3and the walls of to the side portions 14 and I5 by capillary action.

The flux l2 assists both in the capillary action. and in the forming ofa good bond between the material of the bit It! and the material of theinsert l3 with the bonding material l6. After a mounted predeterminedlength of time, the bit is removed from the elevated temperature zoneand rapidly cooled by quenching in oil or molten salt according to thewell-known method of heat treating ferrous material, in order to hardenthe tough portions 14 and 15. Thus, the'bit l0 appears asin the Figure'7 of the drawings. In this figure, it will be seen, that the bitcomprises a bit body III of hardened alloy steel, and having a sideportion l4 and a side portion I5 with a bonded in the groove 1 I by thebonding material groove ll therebetween. The side portions [4 and I5 andthe groove ll merge with the remainder of the active cutting face ll ofthe bit as illustrated. The insert I3 is permanently l6, which hasreplaced the flux material l2.

In the position as illustrated, the insert l3 extends to the tip regionof the bit It, and presents an active cutting edge l8 to contact thematerial to be cut by the tip of the bit. Also apparent from the Figure7, are two side cuttings edges l9 and 20 on the side portions I4 and I5,respectively. These side cutting edges serve to cut and widen a furrowdug by the cutting edge l8 prebe required 7 sented by the insert it.

From past experience, it has been found that the side cutting edges l9and 20 will operate more satisfactorily when inclined at an angle to thesurface being out. That is, the side cutting edges l9 and 20 shouldpreferably have an askew" action. However, when using hard and brittlematerials as' an insert, it has been found that an impact surface ismost operative. Therefore, the insert I3 is positioned at an angle tothe cutting face H, as illustrated in the Figure '7. This relationshipof the side cutting edges 18 and 20 and the end cutting edge I8 isfurther illustrated in the Figure 25.

In the Figure 7, the side portions l4 and I! are illustrated with tworelatively sharp points 2| and 22 on the side portions H and I5respectively. In this particular modification of the invention, thesharp points 2| and 22 are incidental to manufacture. These sharp pointswill soon wear away or break off after the bit It is mounted in thecutter chain and placed in operation. Thereafter the cutting edge illwill be exposed for active cutting service. However, these sharp points2| and 22, as well as a portion of the side portions 14 and I5, may beremoved by grinding before the bit I is placed in operation if desired,as shown in Figure 8. As before indicated, these excess portions areautomatically removed after a period of actual cutting operations, andtherefore, for all intents and purposes the bit I!) may be placed inoperation as illustrated in the Figure 7. After thebit l0 has beenplaced in operation for a period of time, or after the excess portionshave been removed by grinding, the bit will appear as illustrated in theface view in Figure 8. Therefore, although the finished bit as presentedto the operators will preferably be furnished as shown in the Figure 7,the actual working bit will appear substantially as shown in the Figure8.

The insert l3, as before explained, is provided for the purpose offurnishing an end cutting surface for the bit which is extremely durableto prolong the active cutting life of the bit. Therefore, an extremelyhard material is preferable for the insert l3. The type of materialavailable for this purpose includes sintered metal products which havebeen developed and which are suitable for this purpose. Carboloy" is anexample of one such material. These materials are so extremely hard,that practical methods of forming or shaping a product after once beingsintered have not been found. Abrasive action, such as by a grindingwheel, is the only means available today to work or form a sinteredproduct after sinterlng. The sintered material, however, is extremelybrittle and possesses a relatively low tensile strength. Therefore, itmust be protected against .bending stresses and pulling or tensilestresses. The most desirable characteristic of the product, then, is itsextreme hardness and resistance to wear, but it must be protected by abacking surface of a more ductile although softer material, such asferrous products from which the bit to is made.

My improved structure provides the protection required to make the useof a hard metal insert i3 practical. In my structure, the side portionsi4 and i5 protect the sides of the insert l3 in such a manner that sideimpacts against a portion of the insert which is not backed up by abacking member will be prevented. But when the cutting bit is advancingin the direction of its active cutting face I'I', the insert l3 willpresent a cutting edge I8 which will be entirely backed up by thetougher but softer metal of the bit Ill. The portion of the bit l0 lyingdirectly back of the insert l3 and serving as the backing therefor maybe designated as the backing portion 23 of the bit ,I 0.

In operation, as previously explained, the excess material surroundingthe tip of the insert I: will be removed by the abrasive action of thecutting operation. Thereafter, the edge ll of the insert I: will beexposed to contact the surface to be cut. The edge l8 will cut aconsiderably larger quantity of material than the hardenedalloy steelfrom which the bit l0 may be made. As the wearing continues during thecutting operation, the side portions H and I! will be steadily worn backto continually expose more of the insert l3. That is, as the bit movesin its cutting operation, the insert cutting edge l8 will be worn backslowly, but as it is worn back the side portions l4 and I5 will be wornback also to continually expose the cutting edge l8. Also during thecutting operation, the cutting 'edges i9 and 20 of the portions l4 andi5 will remove the side surfaces of the furrow being cut and enlarge thefurrow for the next bit to enter. By this arrangement of parts in myimproved cutting bit, therefore, I have provided a cutting bit having acutting edge which is a composite of at least three cutting edges. Thatis, the cutting edge for the bit as it is produced and illustrated inthe Figure 7, will comprise the side cutting edges l9 and 20 and the endcutting edge 18. These cutting edges constitute a composite cutting edgefor the bit and by the several edges operating in conjunction with oneanother they will contact .the entire surface of the furrow being out.Of course, after a period of use or after the bit I0 is ground asillustrated in the Figure 8, the cutting edge ii of the insert l3 andthe side cutting edges l9 and 20 will be combined to form a continuouscutting edge which will make the entire out together as one unit.

The Figures 9 through 16 illustrate a second alternative method ofproducing a bit in accordance with the principles of my invention. Inthis modification, a recess opening 24 is provided in the bit ID from aflattened end surface 25, and the bottom of the recess extends to theface of the cutting bit. As illustrated, this recess opening 24 isprovided at an angle to the surface I1 substantially the same as theangle which the insert I: will assume in the modification illustrated inthe Figures 1 through 8. An insert 26 is provided to be placed in theopening 24 and is bonded thereto in a manner similar to the methoddiscussed in connection with the bonding of the insert 13 in the groovell. Gases formed during the bonding operation may escape from the recessthrough the bottom thereof. The cutting bit produced by this mode ofconstruction will operate in substantially the same manner as the mannerdescribed in connection with the insert l3, with the possible exceptionthat a protecting surface will be provided by the walls of the opening24 completely around the insert 26 until the end thereof is exposed bywear of the hardened allo steel bit body as previously explained.

The Figures 17 through 24 illustrate still another modification of myinvention in which an opening 24 is cut from the face II inwardly of thebit body backing portion substantially parallel to the edge 21 of thebit It. Again, the bit insert is inserted and bonded to the bit in themanner previously described. Sufiicient clearance is provided betweenthe insert and the side wall of the recess 24 to allow gases to escapeduring the bonding operation.

During the operation of cutting a cleft for the coal with the coalcutting machine carrying the bits thereabout, the bit often encountersan obstruction which will require a smaller cut for each revolution ofthe chains, or an excess of loose materials will bind the machine, orother conditions will happen which will require the cutting chain to bereversed for a period of time in order to free the chain. Thus, thecutting bit ill will not always be operating in a forward position, butwill often be backing up away from its cutting direction. During thisbacking up period, the bit will drag across the surface of the coal, andwill also encounter material which will deliver impact blows to the bit.With cutting machines employing endless chains as described, there is aconsiderable amount of opportunity for the individual links of the chainwhich carry the bits to be displaced from their normal free runningposition when outside forces are experienced. That is, during thecutting operation, a large leverage force is applied to the link and bitdue to the driving force on the link and the dragging force on the tipof the cutter bit. It will readily be seen, therefore, that the linkswill tend to lean over backwards in a direction opposite to thedirection of travel. Therefore, the bit holder and the bit are providedto compensate for this amount of movement and present the bit to thecutting surface at the proper cutting angle. This position isillustrated by the full heavy lines illustrated by the referencecharacter 28 in the Figure 25. Likewise, when the cutting machine isreversed and the drag is on the opposite side of the cutting tip, thelinks will tend to flop over to the other extreme, and is illustrateddiagrammatically by the dot-dash line indicated by the referencecharacter 29 of Figure 25.

As previously explained, the hard material from which the inserts aremade is very brittle and has little resistance to bending stresses,tensile stresses and chipping action. Therefore, a bit constructionwhich does not fully protect the insert from chipping actions on theside thereof, or impacts from the reverse direction on the cutting edge,will allow chipping and consequent destruction of the blts usefulness.My bit construction has taken cognizance of this danger imposed upon thehard metal insert when the bit is traveling in a reverse direction. Itwill be seen, that in each of the three modifications of the cutting bitshown, that if the bit M be tilted into the position as illustrated inthe diagrammatic dot-dash position 29 of Figure 25, a protecting surfaceis provided by the backing portion 23 to take all direct blows andprotect the insert. For example, the bit illustrated in the Figure 25may be considered to be either the modification illustrated in theFigure 7 or the Figure 8 after the bit has been worn to remove theexcess bit material. At all times in the life of the bit, andparticularly after having been worn for some period of time, the bitbacking portion 23 will provide a definite backing for the insert evenat the extreme nd thereof. As wear continues, the portion backing thecutting tip of the insert will be even greater.

In the Figure 25, the dotted line 30 pictures diagrammatically thebottom of a furrow cut in the face 3! of a vein of coal 32. It will beseen, from this illustration that the end of th bit has been worn flaton the tip thereof by the abrasive action of the coal and has provided acorner 33 on the bit backing portion 23. This comer l3 acts as a bumperto ward oil. impact blows and protect the insert when the bit is movingin a reverse direca certain degree of particularity in its preferredform, it is understood that the present disclosure of the preferred formhas been made only by way of example and that numerous changes in thedetails of construction and the combination and arrangement of parts maybe resorted to without departing from the spirit and the scope of theinvention as hereinafter claimed.

What is claimed is:

' 1. A cutting bit, comprising a bit body provided with a cutting endand having an active cutting face and a face backing portion, saidbacking portion having an edge surface approaching said face surface atan acute angle, a recess extending inwardly of said bit, said recessextending from said active cutting face into said backing portion andlying substantially parallel to said backing portion edge surface, ahard metal insert positioned in said recess, said insert being exposableby the wearing away of the active cutting face.

2. A cutting bit, comprising a bit body provided with a cutting end andhaving an active cutting face with side cutting edges and a face backingportion, said backing portion having an edge surface approaching saidface surface at an acute angle, a recess extending inwardly of said bit,said recess extending from said active cutting face into said backingportion and lying substantialhr parallel to said backingportion edgesurface, a hard metal insert positioned in said recess, said insertbeing exposable by the wearing away of the active cutting face, theexposed portion of said insert and said face side cutting edges forminga continuous cutting edge for the bit.

3. A double ended bit comprising a solid piece of metal havingsubstantially parallel side edges and substantially parallel oppositeend cutting faces offset relative to one another, said edges and facesdefining a substantially rhomboidal cutting bit, cutting tips at theopposed sharper angles of the rhomboicl, each of said tips having arecess extending from the cutting face inwardly of the solid metal piecesubstantially parallel to an adjacent side edge, a hard metal insertreceivable in said recess and being bonded to the walls thereof.

HARRY M. MORROW.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,908,161 Meutsch May 9, 19332,255,856 Morrow Sept. 16,1941

FOREIGN PATENTS Number Country Date 606,703 Germany Nov. 22, 1934670,880 Germany Jan. 26, 1939

